A.∀φ∈R,函数y=sin(2x+φ)都不是偶函数 |
B.∃x∈R,使得e2x+3ex+1=0 |
C.∃m∈R,使f(x)=(m-1)•xm2-4m+3是幂函数,且在(0,+∞)上单调递减 |
D.“∃x∈R,使2x>3”的否定是“∃x∈R,使2x≤3” |
π |
2 |
π |
2 |
1 |
x |
A.∃x0∈R,x02-x0+1<0 | B.∀x∈R,x2-x+1>0 |
C.∃x0∈R,x02-x0+1≤0 | D.∀x∈R,x2-x+1≤0 |
A.若a2+b2=0,则a,b全不为0 |
B.若a2+b2≠0,则a,b全不为0 |
C.若a2+b2=0,则a,b不全为0 |
D.若a2+b2≠0,则a,b不全为0 |
A.若p∧q为假,则p,q均为假命题 |
B.“x>2”是“x2-3x+2>0”的充分不必要条件 |
C.对命题p:∃x∈R,使得x2+x+1<0,则¬p为∀x∈R,均有x2+x+1<0 |
D.命题“若x2-3x+2=0,则x=1”的逆否命题为“若x=1,则x2-3x+2≠0”. |
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